CHAPTER XV. 



THE PRODUCTION OF THE VOICE 



BEFORE commencing the consideration of the Nervous system and 

 the Special Senses it will be convenient to consider first speech, the 

 production of the human voice, and the physiology of the Larynx 

 generally. 



The Larynx. In nearly all air-breathing vertebrate animals there 

 are arrangements for the production of sound, or voice., in some parts of 



Cornu min: 

 Cornu ma j' 



Cornu sup: 



<i. Sterno-liyoideus, 



an. Sterno-hyoideusu 



. Sterno-liyoideud, 

 Crico-thyroideus. 



lag: crico-thyr. med: 



Cart: cricoidea. 

 Lag: crico-tracheae. 



Cart: tracheale. 



Fig. 341. The Larynx, as seen from the front, showing the cartilages and ligaments. The mus- 

 cles, with the exception of one crico-thyroid, are cut off short. (Stoerk.) 



the respiratory apparatus. In many animals, the sound admits of being 

 variously modified and altered during and after its production; and, in 

 man, one such modification occurring in obedience to dictates of the 

 cerebrum, is speech. 



It has been proved by observations on living subjects, by means of 

 the laryngoscope (p. 543), as well as by experiments on the larynx taken 

 from the dead body, that the sound of the human voice is the result 

 of the vibration of the inferior laryngeal ligaments, or the true vocal 



536 



